Question

how much gravity is done by a workman carrying a 8kg sheet plywood up a 3m ramp inclined at an angle of 20 degrees to the horizontal?

Answer 1

Work is force times distance. Note that the only work done here is in the direction opposed to gravity, or if you prefer the change in height times the weight...

W=3sin20(8*9.8)

W≈80.44 J